In many patients who suffer from disfunction of the mitral and/or tricuspid valves(s) of the heart, surgical repair of the valve (i.e., "valvuloplasty") is a desirable alternative to valve replacement. One specific group of patients who are typically candidates for such surgery is children who suffer from congenital valvular anomaly (CVA) or rheumatic valvular disease (RVD).
Remodeling of the valve annulus (i.e., "annuloplasty") is central to many reconstructive valvuloplasty procedures. In 1968, Dr. Alain Carpentier published studies which demonstrated that such remodeling of the valve annulus might be accomplished by implantation of a prosthetic ring (i.e. "annuloplasty ring") to stabilize the annulus and to correct or prevent valvular insufficiency that may result from defect disfunction of the valve annulus. Annuloplasty rings are typically constructed of a resilient core covered with a fabric sewing ring. Annuloplasty procedures are performed not only to repair damaged or diseased annuli, but also in conjunction with other procedures, such as leaflet repair.
The prior art has included numerous annuloplasty rings, such as those described in U.S. Pat. Nos.: 4,042,979 (Angell), 4,290,151 (Massana); 4,489,446 (Reed); 4,602,911 (Ahmadi et al.); 5,061,277 (Carpentier et al.); and 5,201,880 (Wright et al.), as well as International Patent Publication WO 91/17721 and Foreign Patent Publication SU 197710.
One problem associated with the anmuloplasty rings of the prior art is that when such annuloplasty rings are implanted into children or adolescents (such as pediatric patients with CVA or RVD) the subsequent growth of the patient may render the annuloplasty ring too small for its intended function, thus abnormally constricting the annulus. The mitral annulus, for example, typically grows from about 16 mm across its longest dimension, to about 34 mm in adults. Follow-up surgery would be necessary to replace the originally implanted annuloplasty ring with a larger ring suitable for the then-current size of the patient. However, the tissue of the heart valve annulus grows into the fabric suture ring by design so that the ring is soon embedded in living tissue, making such replacement surgery problematic. Therefore, reconstructive valvuloplasty surgery on younger patients is often done using just sutures to bolster the annulus, or in conjunction with pieces of woven polyester or other biocompatible material. Such repairs may restore the normal geometry of the annulus, but are unlikely to maintain that geometry without additional structural support, and therefore are associated with less reliable and durable results.
Although some of the annuloplasty rings of the prior art have incorporated means for adjusting the size of the ring at the time of implantation, the inventors are aware of no prior art annuloplasty ring constructed and equipped for post-implantation size adjustment, in situ, to accommodate changes in annular size due to growth of the patient.